To be clear anyone with a few million in savings can take on multiple citizenships as a hobby, maybe OP just considers it table stakes for billionaires, as in, why wouldn't you.

St kitts and Nevis is only a quarter mil, tho I don't know what benefit that would confer unless you're coming from a country without visa free travel

And for what it's worth, UAE citizenship is not for sale directly, you have to actually live there long term

Nice table on this page: https://www.globalcitizensolutions.com/citizenship-by-invest...